1. Field of the Invention
The present invention relates to a cooling device for a projection displaying, more particularly to a cooling device for a reflective liquid crystal image kernel.
2. Description of the Related Art
As the optical electronics technology is developed in a fast growing phase, a general projector device usually uses a high power light bulb as the light source for the projection in order to have a brighter and clearer image on the screen and provide a comfortable view environment to users. However, the high power light bulb creates the problem of high temperature and heat dispersion in the meanwhile. In order to cool the heat generated by the high power light bulb shining on the optical components and further avoid the optical components from deteriorating due to the high temperature, the image kernel of the projection by prior-art projector device uses fans for cooling. However, fans will create another noise problem. Therefore, the way of effectively dispersing heat and reducing noise becomes an important research and development subject for the image projector industry.
Please refer to FIG. 1 and FIG. 2. In FIG. 1, it shows the perspective view of the image kernel 10 for the prior art projector; FIG. 2 is the schematic view of the layout of the corresponding optical components in the image kernel 10 for such prior art projector. The image kernel has a lamp (not shown in the figure) under the image kernel 10 for the projection, and the beam emitted by the lamp as shown in FIG. 2 passes through the optical components such as the X-plate 12, polarizers 131, 132, 133, half wave plates 141, 142, 143, light valves 151, 152, 153 and X-cube 16 in the external case 10 of the projection image kernel 10 for the processing. The X-plate 12 separates the white light into three different color lights: red, blue, and green. These color lights are introduced to three units modulating elements composed of polarizers 131, 132, 133, half-wave plates 141, 142, 143 and light valves 151, 152, 153 for the modulation. The X-cube 16 combines the light and then the light is projected to the screen by the projection lens at the front end of the X-cube. Since the optical components in the projection image kernel 10 for processing the light have been widely used in the industry and also not the feature of the present invention, therefore the process of combining light and their relation are not described here.
When the high intensity light emitted from the aforementioned high power projection lamp passes through the optical components such as the X-plate 12, polarizers 131, 132, 133, half wave plates 141, 142, 143, light valves 151, 152, 153 and X-cube 16, those optical components produce heat of high temperature due to the illumination. The heat must be dispersed effectively to limit the temperature within the appropriate range for the material of those optical components, or else the heat will deteriorate the color and uniformity of the image and reduce the quality of the projection. When it gets more serious, the expensive optical components will be damaged. Although the high intensity light of the foregoing high power projection lamp passes through the optical components along the optical path of the projector, it will generate high-temperature heat. The present invention is to solve the heat dispersion problem of the optical components of the reflection liquid crystal projection kernel 10, and thus the following will only describe the heat dispersion of the reflective liquid crystal image kernel related to the present invention.
In FIG. 1 and FIG. 2, they show that the three light valves 151, 152, 153 of the prior art reflective liquid crystal image kernel 10 are fixed on the front and the two lateral sides of the external case 11, and fans 171, 172 are disposed at the ventilation holes 111, 112 on the aslant surface in the front of the external case 11, and the fans 171 and 172 are disposed between the three light valves 151, 152, 153 and draw air from the outside. The air is blown from three units of modulating elements to the related optical components (the arrow in FIG. 2 indicates the direction of the air flow) so that the heat of the optical components such as the X-plate 12, polarizers 131, 132, 133, half wave plates 141, 142, 143, light valves 151, 152, 153 and X-cube 16 in the external case 11 can be dispersed. However, the top of the external case 11 is sealed, and only the bottom has openings, and the three light valves 151, 152, 153 are fixed on the sides of the external case 11, and most air flow blew between the three modulating elements from the fans 171, 172 only can be blown to the optical components such as the X-plate 12, polarizers 131, 132, 133, half wave plates 141, 142, 143, and X-cube 16, and only a small portion of the reflected air is blown to the inner surface of the three light valves 151, 152, 153, but the air flow is totally unable to be blown to the outer surface of the external case 11. Therefore, it causes non-uniform air flow field in the external case 11 and the light valves 151, 152, 153 cannot disperse heat effectively and will affect the function of optical components such as light valves 151, 152, 153 or even deteriorate the components due to the high-temperature heat and lower the quality of the entire projector. In addition, the optical components on both sides in the case of the reflection liquid crystal projection kernel 10 can disperse heat by using the two fans 171, 172 on both sides. However, they will increase the volume of noise at the same time.